The Cardiovascular System- The Blood Vessels

Which tunic of an artery is most responsible for maintaining blood pressure and continuous blood circulation? tunica externa tunica media tunica intima tunica adventitia

Histologically, the ________ is squamous epithelium supported by a sparse connective tissue layer. tunica intima tunica externa tunica media tunica adventitia

Which statement best describes arteries? All carry oxygenated blood to the heart. All carry blood away from the heart. All contain valves to prevent the backflow of blood. Only large arteries are lined with endothelium.

The arteries that are also called distributing arteries are the ________. arterioles muscular arteries elastic arteries capillaries

The arteries that directly feed into the capillary beds are called ________. muscular arteries elastic arteries venules arterioles

Vasodilation is a widening of the lumen due to smooth muscle contraction. True False

Which of the following is not true regarding fenestrated capillaries? Fenestrated capillaries in endocrine organs allow hormones rapid entry into the blood. Fenestrated capillaries in the small intestine receive nutrients from digested food. Fenestrated capillaries are essential for filtration of blood plasma in the kidney. Fenestrated capillaries form the blood-brain barrier.

A precapillary sphincter is a cuff of smooth muscle that regulates the flow of blood into the capillaries. True False

Peripheral resistance ________. increases as blood viscosity increases decreases with increasing length of the blood vessel increases as blood vessel diameter increases is not a major factor in blood pressure in healthy individuals

An increase in blood viscosity will cause an increase in peripheral resistance. True False

Factors that aid venous return include all except ________. urinary output pressure changes in the thorax activity of skeletal muscles venous valves

Which of the following is likely during vigorous exercise? Blood will be diverted to the digestive organs. The skin will be cold and clammy. Capillaries of the active muscles will be engorged with blood. Blood flow to the kidneys increases.

The velocity of blood flow is ________. slower in the arteries than in capillaries because arteries possess a relatively large diameter slowest in the capillaries because the total cross-sectional area is the greatest slower in the veins than in the capillaries because veins have a large diameter in direct proportion to the total cross-sectional area of the blood vessels

The pulmonary circulation does not directly serve the metabolic needs of body tissues. True False

What layer can change blood vessel diameter by vasodilation and vasoconstriction? tunica media vasa vasorum tunica externa tunica intima

The aorta is an example of a(n) __________. vein arteriole muscular artery elastic artery

What type of tissue is found in the walls of the arteries but not in the walls of capillaries and venules? elastic tissue smooth muscle endothelium collagen fibers

Which type of vessel contains elastin in all three tunics to allow the vessel to expand and recoil as the heart ejects blood? elastic artery arteriole muscular artery distributing artery

Gas and nutrient exchanges between the blood and tissues take place at the __________. veins arteries capillaries arterioles

Which of the following is true about veins? Veins have valves; arteries do not. Veins have a smaller diameter lumen than arteries. Veins are more muscular than arteries. Veins carry blood away from the heart, while arteries carry blood to the heart.

Leaky capillaries found in the bone marrow are called __________. continuous capillaries fenestrated capillaries arterioles sinusoidal capillaries

What type of vessel has relatively little smooth muscle or elastin in the tunica media, a large lumen (average of 5.0 mm in diameter), and thin walls (average of 0.5 mm)? arteriole muscular artery venule vein

Which of the following is NOT an important source of resistance to blood flow? vessel length blood viscosity vessel diameter total blood volume

Why is it important that blood pressure drop to lower levels as it reaches the capillary beds? Because capillaries actually are high-pressure vessels. Because capillaries depend on the lower pressure to prevent fluid exchange between the capillaries and the tissue fluid. Because capillaries are fragile and extremely permeable. Because capillaries actually need a higher blood pressure for filtration activities.

What vessels sustain a drop in pressure from approximately 35 mm Hg to around 17 mm Hg? arterioles veins elastic arteries capillaries

Which of the following would NOT move by diffusion across a capillary endothelium to or from the surrounding interstitial fluid and tissues? carbon dioxide lipid-soluble substances proteins oxygen

Veins carry only oxygen deficient blood. True False